Black diamonds: A guide to value, origin, and types

Black diamonds are valued based on their origin, color, cut, and carat weight. They can be categorized into several types: natural, treated, or lab-grown. Natural black diamonds, which develop their appearance from dense inclusions or fractures, typically command the highest prices, often ranging from $1,000 to over $2,000 per carat. One specific naturally occurring type is carbonado, a polycrystalline form found in regions such as Brazil and Central Africa.

Treated black diamonds are natural stones that have undergone processes like irradiation or annealing to intensify their dark appearance. These generally cost between $300 and $1,000 per carat. Lab-grown black diamonds, created in controlled environments, are more affordable, typically priced between $200 and $600 per carat. Other diamond simulants, such as moissanite and cubic zirconia, serve as less expensive alternatives.

The Gemological Institute of America (GIA) notes that most black diamonds on the market have been treated to achieve their color. Because stones that look similar can have vastly different values, buyers are encouraged to verify origins through documentation, such as GIA reports.